• Journal of the Korean Society of Industry Convergence
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• v.6 no.4
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• pp.401-404
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• 2003

In most resource reservation strategies, which give higher priorities to handoff calls over new calls, new calls are often blocked even though there is plenty of available reserved resource. This causes inefficient resource utilization, especially when there are not so many handoff attempts. In this paper, we propose a new reservationstrategy called soft reservation in which new calls can be allocated to the reserved resource while maintaining the QoS of handoff acceptable. Using an M/M/c/c queuing model, we can see that the proposed strategy provides better performance than the conventional reservation strategy in terms of blocking probability of new call and dropping probability of handoff calls.

• Journal of Korea Multimedia Society
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• v.10 no.9
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• pp.1153-1164
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• 2007

One of the most challenging technical issues in mobile communication for multimedia is Quality of Service (QoS) management of handover calls. This paper proposes a 2-level handover control system to copy with this problem. A 2-level handover control system consists of resource reservation and call admission control modules. The resource reservation module divides the network resource into Hard and Soft reserved resource. The Hard reserved resource is only for the handover calls while the Soft reserved resource is for both the handovers and the new calls. And also, the resource reservation module classifies handovers into primary and secondary handovers based on often they occur. The call admission control module deals with the primary and secondary handover calls in different ways. The new calls can use Soft reserved resource only if there is sufficient amount available in the Hard reserved resource. Proposed system is evaluated using an M/M/c/c queueing model. It is shown that proposed system allows more efficient utilization of network resource without degrading QoS comparing with the legacy handover control systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.2C
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• pp.174-180
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• 2007

In the tone reservation (TR) scheme, it is known that the set of randomly selected peak reduction tones (PRT's) performs better than the contiguous PRT set and the interleaved PRT set in the PAPR reduction of orthogonal frequency division multiplexing (OFDM). It is also known that finding the optimal PRT set corresponds to the secondary peak minimization problem in the TR scheme. However, the problem cannot be solved for the practical number of tones since it is NP-hard. In this paper, a new search algorithm for the near optimal PRT set is proposed based on the fact that the secondary peak value of the PRT set statistically tends to decrease asthe variance of the PRT set decreases.

• Journal of information and communication convergence engineering
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• v.14 no.1
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• pp.21-25
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• 2016

N-screen is a promising technology to improve support for multimedia multicasting, content sharing, content mobility, media scalability, and seamless mobility. In this paper, the WiMedia distributed-MAC (D-MAC) protocol is adopted for development of a seamless N-screen wireless service. Furthermore, to provide a multi-hop, one source multi-use N-screen service through point to point streaming in a seamless D-MAC protocol, a dynamic multi-frame transmission technology is proposed. In this technology, a dynamic time slot allocation scheme and a multi-hop resource reservation scheme are combined. In the proposed dynamic time slot allocation scheme, two thresholds, a hard threshold and a soft threshold, are included to satisfy the power consumption and delay requirements. A multi-frame DRP reservation scheme is proposed to minimize end-to-end delay during the multi-hop transmissions between N-screen devices. The proposed dynamic multi-frame transmission scheme enhances N-screen performance in terms of the multi-hop link establishment success rate and link establishment time compared to the conventional WiMedia D-MAC system.

• Journal of Communications and Networks
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• v.16 no.2
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• pp.130-139
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• 2014

Due to the unpredictable nature of channel availability, carrying delay-sensitive traffic in cognitive radio networks (CRNs) is very challenging. Spectrum leasing of radio resources has been proposed in the so called coordinated CRNs to improve the quality of service (QoS) experienced by secondary users (SUs). In this paper, the performance of coordinated CRNs under fixed-rate with hard-delay-constraints traffic is analyzed. For the adequate and fair performance comparison, call admission control strategies with fractional channel reservation to prioritize ongoing secondary calls over new ones are considered. Maximum Erlang capacity is obtained by optimizing the number of reserved channels. Numerical results reveal that system performance strongly depends on the value of the mean secondary service time relative to the mean primary service time. Additionally, numerical results show that, in CRNs without spectrum leasing, there exists a critical utilization factor of the primary resources from which it is not longer possible to guarantee the required QoS of SUs and, therefore, services with hard delay constraints cannot be even supported in CRNs. Thus, spectrum leasing can be essential for CRN operators to provide the QoS demanded by fixed-rate applications with hard delay constraints. Finally, the cost per capacity Erlang as function of both the utilization factor of the primary resources and the maximum allowed number of simultaneously rented channels is evaluated.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1369-1376
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• 2015

A wireless bridge is essential to transmit control and managing information to sensors or instruments from a central integrated ship area network station. In this paper, a WiMedia Distributed-MAC(D-MAC) protocol is adopted for development of a seamless N-Screen wireless service in Indoor and Ship Area Networks. Furthermore, to provide the OSMU(One Source Multi Use) N-screen service through P2P streaming in the seamless D-MAC protocol, a Dynamic Threshold-based Multicast(DTM) technology is proposed and analyzed. For this technology, a new Hard/Soft Vertical Region(HVR-SVR) based time slot allocation and a multicast resource reservation scheme are combined. From simulation results, proposed DTM scheme expands the number of time slots available for unicast and multicast realtime N-Screen reservations with various service time interval requests. Furthermore, it enhances performances in vewpoints of realtime N-Screen data reservation conflict and throughput.

• Journal of Digital Contents Society
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• v.8 no.3
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• pp.347-353
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• 2007

As the number of channels and programs are increasing dramatically, a viewer seriously needs to book a program at the very time of watching its promotion program by "only one time" pressing remote controller's button. The program reserving system requiring to search a program via EPG is usually hard to operate and some researches that allow a viewer to book a program via its promotion program require additional heavy facilities such as image processing or ultra-frequency recognizing systems. In this paper, a new program reservation system is introduced. the system allows a viewer to book a program via its promotion program. The system is conformable to MHP (which is the data service standard most widely adopted in the world) so that the broadcasting stations need no additional equipments to implement it as long as they follow the MHP standard.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.1
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• pp.283-294
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• 2012

Recently increasing usage of smart phones so, the application field of convergence industry between IT technology using smart phone-based mobile communication networks and other industry branches is expanding. In addition, R&D technologies in other fields are applied to smart phone applications effectively in order to develop products and support daily life more convenient. However, it is very hard to control these products and there is no efficient solution for this problem when many people are sent to specific area for big events, such as Biennale, Film Festival, EXPO, and so on. In order to solve this problem, this paper describes a network-based ticket reservation system and its organization using augmented reality on smart phone and mobile communication networks. In particular, we propose a method of designing and developing prototyping system based on smart phone application design technologies, prior to developing real smart phone application.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.613-616
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• 2006

Development of construction technology and various condition is realized by high-rise buildings and so concrete placing by pressure pump has been developed in with the trend of large-size and high-rise building. So, it is judged that reservation of the basic data for standard of quality control standard Code by the prediction and this to a quality change exact here is urgent. In this study it is going to carry out experimental research for a physical-properties change searching examination of the concrete by the after pressure change factor which does not become hard by the pumping method of construction.

• IE interfaces
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• v.11 no.1
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• pp.155-163
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• 1998

In multiparty multimedia communication, each participant not only receives information from other participants but also generates real-time data streams to distribute to others and therefore the difference between source and destination is not clear in terms of data transmission. During a teleconference session, many sub-multicast trees may be generated to exchange information to specific members within the multicast group and if those sub-multicast trees use the same fixed multicast tree, the blocking probability will be high and it is hard to provide QoS for each sub-multicast group. Also, even though there exits some shortcuts between each sub-multicast group, fixed multicast tree does not allow to use those shortcuts. Thus to overcome these problems. We propose a network resource reservation protocol and show that its effectiveness in terms of blocking probability and network resources usage.